The major emphasis of this proposal is to establish more detailed information on the basic biology of glycophorin as a membrane receptor. Glycophorin is the major sialoglycoprotein (SGP) on the surface of mature red blood cells (RBC) and has long been suspected to act as a receptor for malaria parasites. It is our long range goal that this proposed study will be applied toward the development of a model murine system, not only for the study and eradication of malaria and/or sickle cell disease, but also for the development of a more precise biological definition of glycophorin. The overall objective of this proposal is to determine differential expression and incorporation of each murine sialoglycoprotein and to study their structure and function in the RBC membrane during stages of development. In accomplishing these objectives, the following are herein proposed: 1) To screen for differential gene expression and/or developmentally determined incorporation of each SGP type into both fetal and adult maturing RBC using Western blot analysis and specific staining procedures; 2) To ascertain specific concentration or topographic variances of each type of SGP on the surface of fetal versus adult RBC using labelled antibodies and electron microscopy; 3) To construct a recombinant murine cell system from a cell line which does not ordinarily produce glycophorin, but which will now specifically express glycophorin C on its membrane surface with the aid of polymerase chain reaction and transfection. This recombinant cell system will be used for further studies; 4) To determine the ability of murine glycophorin A and C to act as a receptor for a particular serum protein using affinity chromatography and Western blot analysis. Clearly the significance of this study would be found in its contribution towards a more thorough understanding of how surface membrane components play a crucial role in complex function of the cell.